15.10 Lubrication Systems Flashcards
Are wet or dry sump lubrication systems used gas turbine engines?
Both
How do wet sump lubrication store there oil?
In the engine
How do dry sump lubrication store there oil?
External supply tank
How can the engine oil lubrication systems be classified?
All flow system, constant pressure system
Give two characteristics of the full flow system?
The simplest oil supply system, has no way of regulating oil
How does the pressure change in a full flow system?
Changes in the rotor speed (N2), oil temperature, flow areas downstream of the supply pump
What is an oil cooler installed in the supply line called
Hot tank system
How is the supply pump driven?
The N2 rotor system via the gearbox
What is an oil cooler installed in the scavenge line called?
Cold tank system
How does the N2 rotor and oil pressure correlate?
Faster the N2 rotor spins the higher the oil pressure
What will a leakage cause?
A decreased in oil pressure and quantity
What are the two main types of oil coolers used for turbine engine?
Fuel cooled oil coolers
Air cooled oil coolers
Why is a pressure relief valve installed between the delivery side and the suction side?
To prevent oil pressure from becoming too high
What can I constant pressure system also be called?
Regulated pressure system
What does the pressure regulating involve do in the constant pressure system?
Holds the oil pressure to a given design value at all N2 rotor speed from idle to maximum
Does change in temperature affect pressure in constant?
No
What can the pressure regulating valve also do?
Holds pressure difference between the oil pressure and the vent pressure constant, insures that we have the same flow at all engines speed
What main components in fuel cooled oil cooler
Housing
Cover
Core
What are the advantages of the full flow system?
The full-flow system is the most commonly used system because of its simplicity. Another advantage of this system is that no adjustments are necessary during maintenance of the engine
What are the disadvantages of full flow lubrication systems?
The system needs a large supply pump or a relatively high oil pressure when the engines are at idle. This leads to very high oil pressures at higher speeds
There is a significant rise in oil temperature after a power reduction. The oil removes much of the heat from the bearings. When the power is reduced, the lower flow rate of the oil causes the oil temperatures to increase
Why is the exhaust turbine a critical lubricating point?
Due to high temperatures
How does a capacitance type transmitter work
Uses electronic plates and an electric connector, lower part immersed in oil and has two parts that form capacitor
Where can air cooling be provided from?
Early stages of the compressor
The basic lubrication system has four subsystems what are they?
An oil reservoir and supply system
A scavenge system
A vent system
A monitoring system
What is the purpose of the engine oil system?
To apply oil to lubricate, cool and clean the engine bearings and gearboxes
What are the three subsections of the oil system?
Storage, distribution and indicating
How is the oil tank usually made?
Fabricated from an aluminium alloy coated with a layer of silicone to give sufficient fire resistance
What are two normal ways to fill a tank?
Gravity - Where oil is added to the tank directly through the oil tank filler
pressure - Where a pressurised oil source is connected to a filling manifold. This connection is typically made using specialised adapters or fittings
What is the filler surrounded by?
The scupper
What is a reed type transmitter
Metal tube with a float and multi switch assembly. Metal tune has magnets which show how full tank is based on the floats height
What does a scupper do?
Catches any oil spilled during servicing and drains it to the engine drain mast
Why is there a check valve installed on the filler cap?
Prevents discharge of air and oil through the filler when cap is not correctly fitted
What is the oil pump designed for?
Supply oil under pressure to the parts of the engine that require lubrication
What are the two most common pumps?
The gear pump (most commonly used), the gertor pump
What does SOAP stand for
Spectrometric Oil Analysis Program
The gear type oil pump has only two element what are they?
One for oil pressure and for scavenging
What element does the gretor pump have?
Usually contains a single element for oil pressure and several elements for scavenging oil
Where is the oil pressure regulating valve usually fitted?
On the pressurer side of the pump
Why might a large turbofan engine not have a regulating valve ?
System pressure varies with engine rpm and pump speed .pressure regulator valve is used instead
If an oil cooler is used ,why is it important to use a pressure regulator valve?
The oil cooler is walls are thin and can easily rupture
How does SOAP work
Use spectrometric analysis to identify and quantising the metal particles
What is the purpose of a bypass valve?
Used in conjunction with an oil cooler and is used to maintain proper temperature and pressure by varying flow into the oil cooler filter
What is used to protect the oil pump from FOD ?
Screens
Other than protecting the oil pump what else do screens protect?
Oil nozzles, if the filter is bypassed
What is another name for a screen?
Last chance filter
What do all filters consist of?
Filter housing, removable cover, filter bypass valve, electric or mechanical clogging indicators
What size particles can SOAP detect
0.001mm-0.02mm
What are the two types of chip detectors
Magnetic and manual
What are the two types of chip detectors
Magnetic and manual
How does a magnetic chip detector detect metal
Measures resistance between particles with magnets
What are the two types of transmitters used?
- capacitance type transmitter
- reed switch type transmitter
Why are metal particulates a big problem in oil systems?
Particulars can club pipework, and once one is broken into the oil, it can cause more to break off into the oil, and so on
Why must additives in oil being measured over time
Additives kind of grade or deplete overtime. These additives are important for the oils performance.
What provides information about the internal wear of lubricate the engine parts?
Debris monitoring system
One method is an easier method of detecting FOD between soap and magnetic chip detectors
Magnetic chip detectors
